Conscious sedation, produced by the administration of certain medications, is an altered level of consciousness that still allows a patient to respond to physical stimulation and verbal commands, and to maintain an unassisted airway.
The purpose of conscious sedation is to produce a state of relaxation and/or pain relief by using benzodiazepine-type and narcotic medications, to facilitate performing a procedure such as a biopsy, radiologic imaging study, endoscopic procedure, radiation therapy, or bone marrow aspiration.
Sedation is used inside or outside the operating room . Outside the operating suite, medical specialists use sedation to calm and relax their patients.
If the patient is to undergo a minor surgical procedure, screening and assessment of medical conditions that may interfere with conscious sedation must be explored. These potential risk factors include advanced age, history of adverse reactions to the proposed medications and a past medical history of severe cardiopulmonary (heart/lung) disease.
Once it has been established that the patient would be a good candidate for conscious sedation, just prior to the surgery or procedure, the patient will receive the sedating drug intravenously. A clip-like apparatus will be placed on the patient's finger to monitor oxygen intake during the sedation. This oxygen monitoring is called pulse oximetry and is a valuable continuous monitor of patient oxygenation.
Dosing of medications that produce conscious sedation is individualized, and the medication is administered slowly to gauge a patient's response to the sedative. The two most common medications used to sedate patients for medical procedures are midazolam and fentanyl.
Fentanyl is a medication classified as an opioid narcotic analgesic (pain reliever) that is 50 to 100 times more potent than morphine. Given intravenously, the onset of action of fentanyl is almost immediate, and peak analgesia occurs with in 10 to 15 minutes. A single dose of fentanyl given intravenously can produce good analgesia for only 20 to 45 minutes for most patients because the drug's distribution shifts from the brain (central nervous system) to peripheral tissues. The key to correct dosage is titration, or giving the medication in small amounts until the desired patient response is achieved.
Midazolam is a medication classified as a short-acting benzodiazepine (sedative) that depresses the central nervous system. Midazolam is ineffective for pain and has no analgesic effect during conscious sedation. The drug is a primary choice for conscious sedation because midazolam causes patients to have no recollection of the medical procedure. In general, midazolam has a fast-acting, short-lived sedative effect when given intravenously, achieving sedation within one to five minutes and peaking within 30 minutes. The effects of midazolam typically last one hour but may persist for six hours (including the amnestic effect). Patients who receive midazolam for conscious sedation should not be allowed to drive home after the procedure.
Patient monitoring during conscious sedation must be performed by a trained and licensed health care professional. This clinician must not be involved in the procedure, but should have primary responsibility of monitoring and attending to the patient. Equipment must be in place and organized for monitoring the patient's blood pressure, pulse, respiratory rate, level of consciousness, and, most important, the oxygen saturation (the measure of oxygen perfusion inside the body) with a pulse oximeter (a machine that provides a continuous real-time recording of oxygenation). The oxygen saturation is the most sensitive parameter affected during increased levels of conscious sedation. Vital signs and other pertinent recordings must be monitored before the start of the administration of medications, and then at a minimum of every five minutes thereafter until the procedure is completed. After the procedure has been completed, monitoring should continue every 15 minutes for the first hour after the last dose of medication(s) was administered. After the first hour, monitoring can continue as needed.
The American Academy of Pediatrics (AAP) has established safe practice guidelines to manage conscious sedation without an anesthesiologist for minor procedures. These AAP criteria include (1) a full-time licensed clinician (nurse, physician, physician assistant, surgeon assistant, respiratory therapist) who is strictly and exclusively monitoring the patient's breathing, level of consciousness, vital signs, and airway; (2) standard procedures for monitoring vital signs; and (3) immediate availability (on site) of airway equipment, resuscitative medications, suction apparatus, and supplemental oxygen delivery systems.
If adverse reactions occur while using fentanyl, the antidote is a drug called naloxone. It provides rapid reversal of fentanyl's narcotic effect. The incidence of oversedation or decreased respiration is low using fentanyl if the medication is carefully titrated.
See also Pulse oximeter .
Behrman, R. Nelson Textbook of Pediatrics, 16th ed. Philadelphia: W. B. Saunders Company, 2000.
"Recommended Practices: Monitoring the Patient Receiving IV Conscious Sedation." Association of Operating Room Nurses 57, no. 4 (April 1993).
U. S. Department of Health and Human Services. Acute Pain Management: Operative or Medical Procedures and Trauma. Clinical Practice Guidelines. Department of Health and Human Services Pub. No AHCPR 92-0032.
American Association of Nurse Anesthetists. 222 South Prospect Avenue Park Ridge, IL 60068-4001. Telephone: (847) 692–7050. Fax: (847) 692–6968. E-mail: info@ aana.com.
Laith Farid Gulli, M.D.,M.S. Alfredo Mori, MBBS
Conscious sedation is administered by medical or pediatric specialists performing a procedure that may be diagnostic and/or therapeutic. It may be used in a hospital, outpatient care facility, or doctor's office.